Harvester for headed vegetables

ABSTRACT

A high speed lettuce harvesting machine comprising a vehicle adapted to move along vegetable rows to be harvested, a pair of vegetable head-engaging sensing arms mounted on said vehicle, a plurality of sensor belts mounted on said arms, the sensor belts being adapted to be deflected by the circumference of said vegetable head to guide and actuate a cutting blade toward the stem of the vegetable head so as to sever only fully grown heads and to transport them to a conveyor.

May 8, 1973 United States Patent 1 Coon R 7 2 3 W 5 m m G 8 6 w M 4 3 2w "4w 3 D E D A E H R S E mt TB a mu A .E HV M g Primary Examiner-LouisG. Mancene Assistant Examiner-J. N. Eskovitz Attorney-A. John Michel[76] Inventor: James G. Conn, 68 Madrid Plaza, Mesa, Ariz. 85201 Jan.24, 1972 [21] Appl. No.1 219,975

[22] Filed:

[57] ABSTRACT A high speed lettuce harvesting machine comprising a U SCl vehicle adapted to move along vegetable rows to be harvested, a pairof vegetable head-engaging sensing arms mounted on said vehicle, aplurality of sensor belts mounted on said arms, the sensor belts beingadapted to be deflected by the circumference of said [58] Field ofSearch vegetable head to guide and actuate a cutting blade ReferencesCited UNITED STATES PATENTS toward the stem of the vegetable head so asto sever only fully grown heads and to transport them to a conveyor.

3,380,237 Garrett......... .........1 ....56/D1G. 15

Lawson A 6 Claims, 15 Drawing Figures Patented May 8, 1973 3,731,417

I 5 Sheets-Sheet 2 Patentd May 8, 1973 5 Shoots-Sheet 4 y FE 47,11

IN W

Patented May 8, 1973 5 Shoets-Sheetfi HARVESTER FOR HEADED VEGETABLESThis invention relates to a high-speed machine for the harvesting ofhead lettuce, and other headed vegetables, and more particularly to asensing mechanism for properly selecting and cutting lettuce heads froma row or rows of lettuce in the fields.

It is an object of this invention to provide new and useful means formechanically determining which a heads of lettuce are of a suitable sizeand maturity to be harvested without disturbing the immature heads.

It is another object of this invention to provide an accurate cuttingmechanism as a part of one cycle of operation of a lettuce harvestingmachine, so that one complete cycle of the harvesting machine may beaccomplished only by the effective sensing and selection as to thematurity, firmness and size of the lettuce heads to be harvested.

Another object of the invention is to provide a simple adjustment forthe sensor arms for various size heads of lettuce to be harvested by theharvesting machine.

Another object of this invention is the provision of a mechanism in alettuce harvesting machine for the translation of the severed heads oflettuce from the field row to a conveyor, and the returning of themechanism automatically to its normal position for processing anotherhead of lettuce before another cycle begins.

Another object of the invention is to provide a highspeed harvestingmachine to facilitatethe rapid harvesting of headed vegetables and toincrease the efficiency of harvesting this product, said machine beingmounted on the sides of a conventional tractor for harvesting the crop,and removed from the tractor after harvesting'has been completed, thusfreeing the tractor for other work.

Still another object of the invention is to provide a paratus suitablefor operating a bent or curved cutting blade transverse tothe rows ofvegetables that are to be harvested, the curved part of the bladeconforming to the topography of the sides of the row adjacent to erodedirrigation furrows, so that the cutting blade will sever the heads froma row growing at an angleor leaning toward the irrigation furrow due tothe erosion of the sides of the. row, thereby enabling the cutting ofthe plants'at the base of the heads and without damaging the heads.

Another object of the invention is to provide a harvesting machine thatcan be operated without specially trained personnel, and which is ruggedenough not to require an excessive amount of maintenance.

DRAWINGS These and other objects and advantages of my inven- FIG. 3 is afragmentary plan view of. the'sensing belts,

the sensor arms and their adjustment and actuating V mechanism;

FIG. 4 is a sectional view taken substantially on line 4-4 of FIG. 3,showing the sensorbelts, the sensor arms and cam means at their normalposition;

FIG. 5 is a fragmentary top plan view of the sensing belts, the limitswitch and its actuating plate, the sensor belt mounting and the tensionbrackets, showing a head of lettuce, of the desired size as it deflectsthe sensor belts and actuates the limit switch, the upper part of thearms being cut away for clarity;

FIG. 6 is a sectional view taken substantially on the line 66 of FIG. 5showing the sensor belts deflected outward by the lettuce head, thebelts acting as fingers holding the head of lettuce firmly, to besevered from its stem and then lifted by the arms from the row oflettuce being harvested;

FIG. 7 is a top plan view of the cutting mechanism showing the cuttingblade in its :normal position, i.e.

transverse to the rows of lettuce lbeing harvested; this view also showsthe cutting blade positioning arms, the sensor arms and the actuatingmechanism;

FIG. 8 is a fragmentary side elevation of the cutterpositioning arms indownward position with the cutting blade at its full stroke, the sensingarms being at their normal position for the head sensing operation;

FIG. 9 is a fragmentary front elevational view of the sensor belts andsensing arms with the cutting blade and blade-positioning arms in theirnormal or inoperative position, looking toward the rear, showing arejected head of lettuce that will pass between the sensor belts andunder the cutting blade as the harvesting machine moves forward towardthe observer along a row of headed vegetables;

FIG. 10 is a diagramatic view of the curved cutting blade in action andsevering'a lettuce head that has grown at an angle toward the irrigationfurrow, caused by the erosion of the soil by water;

FIG. 11 is a fragmentary sideelevation depicting the removal of asevered head of lettuce from the row of plants and then its removal fromthe sensor head by therecovery arms which place the heads on theconveyor; shown also is the actuating mechanism for the lifting of thesensing arms;

FIG. 12 is a fragmentary top plan view of the reciprocating mechanismand driving means for the recovery arms, and for the removing of thesevered heads of lettuce from the sensing arms and-belts;

FIG. 13 is a fragmentary side elevation of the flywheel showing theclutching and declutching mechanismand the limiting switches that permitonly one cycle of the harvesting machine at a time;

FIG. 14 is a fragmentary front elevation of the flywheel showing the camside of the releasing and resetting'arm for driving the cam shaft andthe harvesting machine intermittently during one cycle or revolution,each time a head of lettuce is to be harvested by the machine;

FIG. 15 is a fragmentary perspective view taken somewhat from the rearlooking toward the front of the sensor arm and belts, showing theswitch-actuating plate mounted between the sensor belts and theirpulleys and showing a coil spring urging the plate to the inner sides ofthe sensor belts on the sensingside of the arm.

DESCRIPTION OF PREFERRED EMBODIMENT Referring first 'to FIG. 1, twolettuce harvesting machines are shown mounted, one on each side of aconventional tractor 16, the machine on the far side being mostlyobscured by the tractor. In this embodiment of the invention, thetractor 16 serves as the carrier for the harvesting machine to bedescribed herein and which is indicated generally by reference numeral125. It will be understood by those skilled in the art that variousmodifications may be resorted to in mounting the harvesting machine ormachines.

For example, the harvester may be mounted on a completely self-containedunit or mounted as a trailed unit with or without a separate powersource for its operation. If the carrier is a conventional tractor, thelettuce harvesting machines may be removed therefrom after harvestingand the tractor may be used for other purposes; subsequently, atharvesting time, the harvester may be replaced on the tractor.

The harvester 125 comprises substantially: vertical side support-plates,i.e. inside plate 32, intermediate plate 30 and outside plate 31, whichalso provide bearing supports for a plurality of shafts as shown. Theplates 30 and 32 are fastened together by a channel member 33 and a rearlower angle plate 34 (FIG. 1) and by spacer bars 35 and 36 (FIG. 2). Theoutside plate 31 is supported by and attached to plate 30 by spacer andsupport bars 102 and channel brackets 106 shown in FIG. 12. The verticalplates are attached together to form the frame or body of the lettuceharvesting machine. For reasons of clarity plates 30 and 31, (FIG. 1)have been cut away in order to show the various mechanisms in moredetail.

Attached to the upper surface of the longitudinal channel member 33(FIG. 1) is an L-shaped bracket 37 supporting a hydraulic motor 29attached thereto and driving shaft 45 upon which is mounted and keyed aspur gear 44. Gear 44 meshes with spur gear 43 which is keyed to shaft28 mounted in journal bearings on the frame of the machine. At the endof shaft 28 there is mounted a belt pulley 26 driving belt 25 and pulley24 fixed to the end of shaft 27. Shaft 27 is mounted in journal bearingson the frame of the machine. in the upper rear area of the body as shownin FIGS. 1 and 2. Keyed or otherwise secured to shaft 27 is an elongatedgrooved pulley 39, having assembled on it a plurality of endless belts40 extending around another elongated grooved pulley 41 keyed to shaft42. Shaft 42 is mounted in journal bearings on inner side plate 32 andintermediate plate 30 in the upperfront area of the machine body asshown in FIGS. 1 and 2. Shaft 28 drives pulley shaft 27 and pulley 39 bymeans of belts 40 of the conveyor 22. The conveyor 22 is positionedparallel with and above the rows of lettuce that the.

machine is gathering.

Keyed to the hydraulic drive shaft 45 is drive pulley 46 which drivesbelt 47 and flywheel 51 in counterclockwise direction, thus rotating theflywheel 51 which is mounted on the cam shaft 49 in journal bearings ofthe frame or body of the machine 125.

FIG. 2 shows the hydraulic line 38 that operates the motor 29 with thefluid from the hydraulic system of tractor 16.

Assembly 17 of FIG. 1 is shown in more detail in FIG. 3, in which eachof the sensing arms 58, 59, carries a sensor belt assembly 21 at itsforward end.

Sensing arms 58, 59 are attached by pivot pins 63 to rocker arm 60mounted on shaft 55. Shaft 55 is supported in bearings on side supports30 and 32 of the harvesting machine body. Also shown in FIGS. 3 and 4are: cam 52 keyed to shaft 49; swivel nuts 64 assembled to sensing arms58, 59 by means of adjusting screw 61 provided with right and left handscrew threads for moving or adjusting the arms 58, 59 inward or outwardat the same time for different sizes of heads of lettuce to beharvested; nuts 62 which are provided for manually setting and lockingthe arms 58, 59 in the position desired according to the size of lettuceheads to be harvested by the machine.

FIG. 4 shows sensing arm 59 in a normal position with reference to theground and head 80, also cam 52 with its cam track or groove 122 in itsnormal position with reference to cam follower roller 78 in rocker arm60.

FIG. 5 (which is a fragmentary top plan view) shows arms 58, 59 with theupper section of the housing removed; a lettuce head 80 is being sensedfor size by the sensor belts 72 around the elongated pulley systems 71and 73 rotatable on vertical shafts and 75 assembled in arm 58; thevertical shaft 75 and pulley 73 with belts 72 are assembled in theadjustable tension bracket 74 which is pivotable about bolts 81, 82 andmovable radially for any desired increase or decrease of tension onbelts 72, whereupon it may be locked by bolts 81 and 82 which positionthe belts 72 at an angle to the row of lettuce that is being harvested.

In the sensor section of arm 59 is assembled vertical shaft 69cooperating with grooved pulley 68 carrying a series of sensor belts 72in the front end of arm 59 with sensor belts 72 extending to and aroundgrooved pulley 65 on shaft 76 in adjustable tension bracket 66 andassembled in the sensor section of arm 59 by upper and lower bolts 81and 82 the tension bracket 66 being movable radially about bolts 82 fora desired tension on sensor belts 72 then tightened into position bybolts 81 and 82, positioning belts 72 at a desired angle to the lettuceheads to be harvested forming an angled entrance way for the lettuceheads to enter for sensing and severing. On upper plate of arm 59 thereis mounted a normally open snap action switch 79 and vertically mountedswitch actuator plate 67.

In FIG. 5, 'a head of lettuce of sufficient size and firmness hasentered the sensing belts 72, deflecting some ofthe belts 72 on each ofthe arms 58 and 59, moving the plate 67 to the switch arm and activatingthe switch 79 for a signal to energize the solenoid 108 (FIG. 13) tostart the cycle of the machine to sever the head of lettuce from itsstem or stalk at this instant. FIG. 6 (which is a sectional viewsubstantially taken on line 6-6 of FIG. 5) shows the sensor belts 72being deflected by the lettuce head 80. It is seen that the sensor belts72 are acting as fingers around the lettuce head 80 while knife 94(FIGS. 7,8) moves into position for cutting the lettuce head while thearms 58, 59 lift the head from the row of lettuce that is beingharvested (FIG. 11).

FIG. 7 shows a top plan view of the cutting mechanism assembly 18 withthe sensing and lifting arms 17 assembled on the rocker shaft 55. Theflywheel 51 is shown mounted on the cam shaft 49 along with cams 52, 53and 54 which are mounted as shown on shaft 49. Rocker shaft 55 carriessleeve 126, and on the central part of sleeve 126 is mounted the rockerarm 60; on each side of the rocker arm 60 on the sleeve 126 are mountedthe cutting blade positioning arms 88 and 89 which are adapted to therocker arm 60 in a fixed position and are free to rotate about sleeve126, it being noted that the sleeve 126 with the arm 60 and the arms 88and 89 are free to rotate around shaft 55.

Fixedly secured to the rocker arm shaft 55 on the outside of andadjacent to the cutting blade positioning arms 88 and 89 are crank arms85 and 87 holding the sleeve 126 with the assembled arms 60, 88 and 89in a lateral position on the shaft 55. Connected to crank arms 85 and 87are two rod-end yokes 90 with push rods 86 respectively extending to andconnected to the sliding brackets 93 that support the cutting blade 94;these brackets 93 have a pair of rollers 92 assembled on them and aremovable in the slots of arms 88, 89. The rollers 92 impart a rollingaction to the cutting blade when it is severing a head of lettuce athigh speed. The cutting blade 94 is positioned at all times transverselyto the rows of lettuce being harvested and is in the same position whenthe push rods 86 move the blade forward for the severing action. Themechanisms shown in FIG. 7 are at their normal position.

FIG. 8 is a side elevational view of FIG. 7 showing that: cam 53 hasrotated and has placed the blade-positioning arms 88 and 89 downward tothe severing position, by the action of the cam follower roller 78 (FIG.4) in the cam track 124; the profile cam 54 in contact with the followerroller 95 has pushed the arms 85 and 87 forward, along with push rods86, brackets 93 and the cutting blade 94, i.e. forward along the row oflettuce at the ground level, the cutting blade 94 traveling underneaththe sensing arms 58, 59, i.e. in readiness for the severing stroke ofthe blade 94 while the sensor belts 72 are holding the head of lettucefor severing,

FIG. 9 is a fragmentary front elevational view, looking toward the rearof the harvesting machine with part of the sensor belts 72 cut away toshow the curved and bent cutting blade 94 in its normal positionsupported by the arms 88 and 89 with a small head of immature lettuce inthe passageway and passing undisturbed under the cutting blade 94 forfurther growth and harvesting at a later time.

FIG. 10 is a diagrammatic view of the curved or bent cutting blade 94traversing the row of lettuce and depicting the severing of a head oflettuce that has grown in a leaning position i.e. by the erosion of thesoil at its stem or root such as by the water in the irrigation furrow127, and showing the severing of the head of lettuce at its base with noinjury to the head despite its variation from the normal.

FIG. 1 1 is a fragmentary side elevational view depicting thetranslation of a sensed and severed head of let tuce lifted from the rowof lettuce that-is being harvested. The cam 52 has been rotated, shaft49 moving arm 60 and cam follower roller 78 in cam track or groove 122,in a downward movement, thus raising the attached sensing arms 58 and59, holding a severed head of lettuce for its disposition to theconveyor 40.

FIG. 12 is a top plan view of the recovery mechanism for the removing ofthe head of lettuce from the raised sensing arms (only 58 being shown)and placing the heads on the conveyor belt 40 and thence to the storagecontainer. The recovery arms 57 are rotated in the up position, thecylindrical cam 50, by its cam track 123 guiding the follower roller 98,and sliding bracket 96 on guide rods 48, toward the side plate 31 of theframe of the machine 125; the rack gear 97 on the upper surface of thebracket 96 drives the spur gear 99 keyed to shaft 100, mounted inbearings 105, on support brackets 106. On the opposite end of the shaft100 there is provided a miter gear 201 meshing with miter gear 101 onshaft 56 which is supported by bearings 103 on the side plates 30 and 31 of the body of the machine 125, and extending transversely through thebody of the machine; the recovery arms 57 are adjusted and fixedlaterally on the shaft 56 for different sizes of heads of lettuce to beharvested. The recovery arms 57 are adapted to remove the head oflettuce from the sensing arms 58 and 59 (FIG. 11) by their rotationthrough 180 degrees forward and upwards, and thus place the heads on theconveyor belts 40. The driving mechanism assembly 19 is further drivenby the cam 50, and rotating arms 57, back to its starting position foranother cycle of the machine. Guard 23 is provided to keep the lettuceheads on the arms 57 when the heads are being removed from the sensingarms 58 and 59 and being placed on the conveyor.

F 1G. 13 is a fragmentary side elevational detail view of the assembly20 illustrating the clutching and declutching mechanism 20 and showingthe vertically mounted support plate 107, supported by spacer bars 116,attached to the side body plate 32, the releasing and resetting arm 113which is pivoted and attached to j the plate 107. About midway betweenthe shaft 49 and the pivot point of arm 1 13 are connected two arms 112; the lower ends of arms 112 are pinned to the upper end of arm 111,fonning a hinged joint between them. The lower end of arm 111 is pivotedonto plate 107, thus forming a yoke type lever. On the lower side ofplate 107 there is mounted a normally closed limit snap-action switch109 adjustable with respect to arm 111; on the opposite side of arm 11 1there is mounted a tension spring 110. Close to the hinge point of arm111 there is provided the plunger rod 208 of solenoid 108, the body ofthe solenoid 108 being assembled to the support plate 107. The normallyopen-limit switch 79 is mounted on the sensing arm 59. When switch 79 isactivated, current will flow through the normally closed limit switch109 to energize the solenoid 108, causing its plunger 208 to pull theyoke arms 111 and 112 toward it and thus moving arm 113 downward fromthe cam shaft 49 by a small but sufficient distance to release thespring-loaded key 115; at this instant, the arm 111 activates the limitswitch 109, breaking the current flow to the solenoid 108 anddeenergizes it. The tension spring immediately pulls back the arms 111and 112, and thus restores the arm 113 to its normal position. As theend of one revolution approaches, the spring-loaded key 115, beingengaged in the key slots of the flywheel 51, is. pulled from the keyslots in the flywheel by the sharp pointed cam section of the arm 113,thus resetting the key for another cycle of the machine.

FIG. 14 is a fragmentary front elevation of the flywheel 51, lookingtowards the rear. As may be seen from this view, the end of the arm 113,with its tapered side cam of arm 113 and the key 115 in the key slot ofthe cam shaft 49, rests on the side of the release arm 113, and is readyto be released by the sequence of operations resulting from the arms 58and 59 sensing another mature head of lettuce to be harvested asdescribed above.

FIG. is a fragmentary perspective view of assembly 21, looking somewhatfrom the rear toward the front end of the sensing arm 59, and showingthe switch-activating plate 67, the vertical shaft 119, the coil spring120, assembled in the arm 59, the sensor belts 72, the upper end ofspring 120 holding the plate 67 against the inside of the belts 72 ontheir sensing side until a full-grown head of lettuce deflects the belts72 to make the plate 67 activate the switch '79 (FlG. l3).

OPERATION The operation of this invention is substantially as follows:Assuming that the sensing mechanism assembly 17 with sensing arms 58,59, is in the appropriate position for harvesting and that the vehiclemoves forward in the direction of the arrow 121 (H0. 1) along the row orrows of lettuce to be harvested, with the flywheel on shaft 49 beingrotated by the hydraulic motor 29; (the hydraulic power being suppliedby the hydraulic system of tractor 17). The conveyor belts 40 are alsodriven by the hydraulic motor 29, the driving mechanism of conveyor 22is driven by the power take-off shaft of the tractor 16.

Also assume that the sensing arms 58, 59 are pre-adjusted by theadjusting screw 61, and locked in position by nuts 62, for a particularsize head of lettuce to be harvested. As the machine moves forward andthe arms 58 and 59 contact a head of lettuce in the passageway, thesensor belts 72 being free to rotate with their pulleys on their shafts:if the head of lettuce being sensed is of sufficient size and firmnessit not only contacts the belts 72, but it deflects the belts 72 enoughto move the switch plate 67, thus activating the switch 79 which isnormally open. The switch being now closed by plate 67, solenoid 108is'energized, releasing the clutch key 115, and clutching the shaft 49,and the flywheel 51, which rotates the shaft 49, with the cams 50, 52,53 and 54. Said cams are fixed to the cam shaft 49, for their sequencein operating the mechanisms during one revolution of the shaft 49,completing a cycle of the machine. At the start of the revolution of theshaft 49, cam 53 lowers arms 88, 89 into the position shown in FIG. 8,thereupon the cam 54 actuates the cutting mechanism, driving the cuttingblade 94 forward and under the sensing arms 58, 59, severing the head oflettuce from its stalk while the sensed head is being held in the sensorbelts 72. Next, cam 52 actuates the arms 58, 59 to their upper positionfor removing the severed head of lettuce from the row of lettuce that isbeing harvested, In the meantime, cams 53 and 54 have moved the cuttingmechanism back to its normal position (FIG. 2); next, cam 50 actuatesthe drive mechanism (FIG. 12) moving the arms 57 forward between thesensor belts 72, removing the lettuce head from the sensor arms 58, 59,and placing the heads of lettuce on the conveyor belts 40, whence theyare conveyed to the packing container. In the meantime cam 52 has movedthe arms 58, 59 back to their normal position and at the same time cam50 has returned the arms 57 back to their starting position; the key isextracted from the flywheel key slots by the arm 113, and the clutch key115 is reset for another cycle of the harvesting machine. The completecycle of the machine has been completed within one revolution of the camshaft 49; the cycling operation of the machine being very fast, theflywheel 51, revolving constantly, is possessed of sufficient momentumto maintain the continuous rotary velocity of cam shaft 49 which iscoupled thereto.

it will be understood that various changes may be made in the form,details, arrangements, proportions and number of the parts describedabove without departing from the spirit and scope of my invention as setforth in the appended claims.

What is claimed is:

1. A high speed machine for harvesting headed vegetables, comprising; 7

a vehicle adapted to be guided along vegetable rows to be harvested;

a pair of vegetable head-engaging sensing arms mounted upon saidvehicle;

said sensing arms being provided with horizontal adjustment means forvarious sizes of vegetable heads, and with means for rigidly lockingsaid sensor arms into a horizontal position for a particular size ofvegetable head to be harvested;

said sensing arms being further provided with a plurality of rotatablebelts, attached to, and in an angular position on, the inner verticalsides of the adjustable sensing arms;

said sensing arms comprising means for exerting a predetermined tensionon said rotatable belts;

said belts being rotated and deflected around the sides of the vegetablehead as said head moves into the sensing arms in conformity with thesize and firmness of the head being sensed;

cutting means provided for the severing of the mature heads sensed bysaid sensing arms while being held in a rigid positionv by said arms;

said sensing arms comprising means for lifting the severed heads fromthe rows and for the removal of the severed heads from said sensingarms.

2. Harvester as claimed in claim 1 in which said cutting means comprisesa partially curved cutting blade positioned transverse to the row ofheads of vegetable to be harvested, and means for positioning said bladetransverse to the heads and for severing said heads at their base.

3. Harvester as claimed in claim 1 comprising means for providingangular and tension adjustments on said plurality of rotatable beltssaid means being attached, on vertical pulleys, to the inner surfaces ofthe adjustable sensing arms to provide bracket adjustments on said beltsfor providing an angular fixed space between the sensing arms for theentrance of the head of lettuce to be sensed for severing or rejection.

4. Harvester as claimed in claim 1 comprising an angular space definedby said rotatable belts between said sensing arms, the rotatable beltsbeing rotated by the size and firmness of the heads of lettuce enteringthe larger opening of said space, said heads contacting said belts androtating said belts as they move toward the smaller space.

for automatically transmitting an. electrical impulse to anelectromagnet for the severing of a head which is of sufficient firmnessand size so as to deflect the prestressed belts of said sensing arms,and means for radially lifting the severed heads from the vegetable rowsto a position above the rows while being held firmly, for their removal.

1. A high speed machine for harvesting headed vegetables, comprising; avehicle adapted to be guided along vegetable rows to be harvested; apair of vegetable head-engaging sensing arms mounted upon said vehicle;said sensing arms being provided with horizontal adjustment means forvarious sizes of vegetable heads, and with means for rigidly lockingsaid sensor arms into a horizontal position for a particular size ofvegetable head to be harvested; said sensing arms being further providedwith a plurality of rotatable belts, attached to, and in an angularposition on, the inner vertical sides of the adjustable sensing arms;said sensing arms comprising means for exerting a predetermined tensionon said rotatable belts; said belts being rotated and deflected aroundthe sides of the vegetable head as said head moves into the sensing armsin conformity with the size and firmness of the head being sensed;cutting means provided for the severing of the mature heads sensed bysaid sensing arms while being held in a rigid position by said arms;said sensing arms comprising means for lifting the severed heads fromthe rows and for the removal of the severed heads from said sensingarms.
 2. Harvester as claimed in claim 1 in which said cutting meanscomprises a partially curved cutting blade positioned transverse to therow of heads of vegetable to be harvested, and means for positioningsaid blade transverse to the heads and for severing said heads at theirbase.
 3. Harvester as claimed in claim 1 comprising means for providingangular and tension adjustments on said plurality of rotatable beltssaid means being attached, on vertical pulleys, to the inner surfaces ofthe adjustable sensing arms to provide bracket adjustments on said beltsfor providing an angular fixed space between the sensing arms for theentrance of the head of lettuce to be sensed for severing or rejection.4. Harvester as claimed in claim 1 comprising an angular space definedby said rotatable belts between said sensing arms, the rotatable beltsbeing rotated by the size and firmness of the heads of lettuce enteringthe larger opening of said space, said heads contacting said belts androtating said belts as they move toward the smaller space.
 5. Harvesteras claimed in claim 4 comprising angularly spaced means between thesensing arms which, during the forward movement of the machine, forcethe mature heads into such angular space between the sensing arms, thusdeflecting the belts adjacent to the sides of the mature heads for thesensing action, and severing the heads while being held in a rigidposition.
 6. Harvester as claimed in claim 3 comprising means forautomatically transmitting an electrical impulse to an electromagnet forthe severing of a head which is of sufficient firmness and size so as todeflect the prestressed belts of said sensing arms, and means forradially lifting the severed heads from the vegetable rows to a positionaBove the rows while being held firmly, for their removal.